Various methods are known in order to fasten the bristle tufts in the bristle carrier of toothbrushes, wherein usually injection-molding from plastic is used. There are known the so-called anchor tufting methods, in which the bristles of a tuft are bent, in the shape of a U, around a retaining web which is then driven into a blind hole. There are also known the so-called hot-tufting methods, in which the bristle tufts are anchored on the bristle carrier by means of a forming technique. Usually, the bristle tufts are melted at their ends to form thickenings and then are over-molded with plastic or cast into the head when the brush head is injection-molded.
Such hot-tufting methods have various advantages, for example with respect to hygiene, because less bacteria can collect in the anchoring areas, or also with respect to the cross-sectional geometry of the bristle tufts, which can be designed in greater variety than with the anchor tufting methods. But, it is not easy to generate bristle fields with different properties in different areas using the hot-tufting method. In order to optimize the cleaning efficiency of toothbrushes, it may be helpful to provide different cleaning elements or bristle tufts in different sections of the bristle field. It can be also helpful support cleaning elements or bristle tufts in a different manner, for example to support a portion thereof rigidly in a section of hard plastic and another portion thereof flexibly in a section of soft plastic. In addition, it may also be beneficial to melt the ends of differently composed bristle tufts, for example consisting of different bristle material, to different degrees, in order to achieve an optimum anchoring. However, this is difficult using hot-tufting methods which melt the ends of the tufts after the tufts have been configured into a bristle field, because the usually required application of heat to a bristle tuft always also affects adjacent tuft ends.
A hot-tufting method is known, in which the bristle tufts that are held ready in the form of a bristle field are melted at their ends to such an extent that the melted material of adjacent bristle tufts combines. The resulting flat support structure, which connects the bristle tufts, is intended to achieve an increased pull-out resistance. However, it is difficult in this case to use bristle tufts of differing bristle materials in order to achieve different properties in different bristle field sections, since different types of bristle materials cannot easily be fused together. This becomes even more difficult when not only bristle tufts but also differently designed cleaning elements, such as strips of soft plastic, are to be used and to be combined, for example, with bristle tufts. In addition, the flat support structure on the bottom of the bristle tufts inhibits quick filling of the mold cavities when the bristle carrier is injection-molded.
Accordingly, there is a need for a toothbrush head and manufacturing method thereof, which allows for design flexibility, material flexibility, and support flexibility.